Method of manufacturing a connector tubular splice with worked inner serrations



some suitable tool on the conductor.

Patented May`8, 1945 TOR TUBULAR SPLICE WITH INNER ,SERRATIONS Marvin Lee, Rye, and :Irving Frederick Matthysse, Bronx, N. Y., assignors to Burndy Engineering Company, Inc., a corporation of New Yori; i

Application January 17, 1942, Serial No. 427,130

1 Claim.

This invention relates to connector splices for wires and more particularly to a method of manufacturing an electrical connector.' f

Hitherto it has been found desirable to introduce hard particles on the inner surface of the tubular sleeve, whichv keyed the conductor to the sleeve when the sleeve-was compressed by These methods have always resulted in producing additional contact layers and particles of lower conductivity than the connector wall. thus increasing the resistance of the connection and lowerinf.r the electrical joint efficiency.

We have discovered that it is possible to cold Y work the inner metal surface of the tubular sleeve and produce hardened irregularities which will key into the conductor when the sleeve is compressed.

A primary purpose of our invention therefore is to compress a tubular 4sleeve on a mandrel having suitable serrations. which will cause a cold working of the inner surface of. thc tubular sleeve and harden itin the desired form.

Another object is to provide means whereby the mandrel may be removed after the sleeve has been worked thereon.

We'accomplish these and other objects and obtain our new results as will be apparent from the device described in the following specification, particularly pointed out in the attached claim, and illustrated in the accompanying drawing, in which:

Fig. 1 is a longitudinal sectional view of a die compressing the connector sleeve to a mandrel.

Fig. 2 is a sectional view of the same taken .along line 2--2 of Fig. 1 and in the direction in- Fig. '7 and 8 illustrate a method of compres'- Figs. 11 and 12 illustrate a longitudinal sec- 55 WORKED tional view of a method of rolling a sleeve on a longitudinally rounded mandrel. t

Fig. 13 is, a transverse sectional view of the same.

Fig. 14 illustrates a top view of a sleeve compressed onto a pair of wires. z Fig. 15 is a longitudinal sectional view of the same.

Referring more particularly to the drawing, reference numeral l0 designates a tubular metal sleeve with a bore II, and a. mandrel I2 provided with longitudinal serrations I3 circumferentially arranged thereabout. Thev bore II is slightly larger than the mandrel which is inserted therein, and a pair of compressing dies I4 and I 5 are appliedto the external surface of the sleeve to cause the inner surface of the bore II to assume the serrated form of the mandrel I2. The sleeve and mandrel may be rotated in the dies, to give the entire inner surface of the sleeve the serrated form.

Since the serrations I3 of the mandrel I2 are longitudinal to its axis, the mandrel maybe lateraily withdrawn from the sleeve. This is accomplished by applying a cylindrical tool I6 to the mandrel I2, and forcing the sleeve I0 against a plate I1, having an aperture I8, through which the mandrel I2 -is forcibly Withdrawn. This leaves the tubular sleeve 'I0 with hardened longitudinal serrations intact. 1

'Ihe mandrel may be narrowed at one end, as'

at I3a., and forced through the tubular sleeve I0,vthe gradually increasing diameter, I3b, working the inner surface into the desired shape. 'I'his is possible with longitudinally extending serrasleeve 20, is provided. with threaded serrations 23 which are formed into the worked inner surface of the tubular sleeve by the compressing action of the dies.

In Fig, 5, we have shown a sectional view of a collapsible type of mandrel inserted in a tubular sleeve 25. Here the mandrel isl provided with aplurality of circumferential segments 26, and an inner cylindrical member 21 which may be withdrawn causing the outer segments to collapse and permit their withdrawal. The inner cylindrical member 21 may be provided with may be roughened at surfaces 35 and 38 to insure rolling the sleeve. When the action is completed, the slightly ovalized sleeve is placed in rounding dies 31 and 38 as shown in Fig. 10, which are provided with sockets 38 and 40 for shaping the sleeve in the full round c`ndition to permit the mandrel to be removed from the sleeve.

-An additional method of working the sleeve on the mandrel to produce the desired inner serrations', is shown in Figs. 7 to` 9. Here the compressing dies 42 and 43 compress the sleeve 44 on the mandrel 45 so that inner serrations are caused on two opposite longitudinal regions of contact. This ovalizes the tubular sleeve, as shown in Fig. 8, -which thereafter is rotated 90 and recompressed, causing an additional two regions of serrations The sleeve and mandrel may be rotated to secure any numberof impressions with corresponding serrations. Thereafter the sleeve and mandrel are placed in a rounding die as previously explained, and illustrated in Fig. l0, where the mandrel may/be re-v moved. Y

One more method of working serrations on the inner surface of a sleeve is shown in Figs. 11, 12, and 13. Here the mandrel 46 is inserted into the connector sleeve 41 and supported at each end 48 and 49. A roller 50 is rolled over the outer surface of the sleeve 41, causing the sleeve and mandrel to roll with it. The serrations are actually rolled into the inner 'surface as the roller 50 rotates. Since the mandrel is unsupported at the center thereof, it may be made slightly rounded longitudinally, so .that the compressing force The mandrel should, of course, be made of inetal considerably harder than the sleeve.

A compressing tool for causing indentations on l yknown in the prior art.

By use of interrupted indentations, as shown inl Fig. 14 and Fig. 1'5, the longitudinally applied internal worked serrations may be compressed into the conductor, and act to resist the tensile tions in the inner sleeve without changing the sleeve diameter. This would not interfere with Vthe entrance of the wires to be spliced, and possibly affect the cross-section of the wire least.

forces applied to the conductor without reducing the net cross-section of the conductor. s By using our method of cold working the -inner surface of the sleeve, we have obtained a method of splicing connectors to wires that reaches ultimate results both as to pull out values and as to the electrical joint efficiency. The keys are actually of the same metal as the sleeve and consequently vpossess the same conductivity.

The connector may be of the splice type for joining'two wires, of the terminal or dead end type for joining a single wire to a plate or rod.

We have thus described our invention, but we desire it understoodthat it is not confined to the particular forms or uses shown and described, the same being merely illustrative, and that the invention may be carried out in other ways without departing from the spirit of our invention, and, therefore, we claim broadly the right to employ 4 all equivalent instrumentalities coming within the scope of the appended claim, and by means of which, objects of our invention are attained and new results accomplished, as it is obvious that the particular embodiments herein shown and described are only some of the many thatcan be .employed to attain these objects and accomplish these results. f

What we claim and desire to secure by Letters Patent is as follows:

'I'he method of manufacturing an electrical connector for attachment to a conductor by indentation, which comprises the step of providing a seamless cylindrically shaped sleeve having smooth sides and made of malleable metal hardenable by swedging and suitable for transmitting a current therethrough, and work-hardening by swedging the metal forming the inner surface with a series of irregularities projecting from the inside of the sleeve, from. end to end and increasing the hardness of the metal to a degree sufficient to penetrate the conductor, to provide.

work-hardened keying-in sections suitable for indentation into the conductor by compression.

mviNG FREDERICK MATrHYssE. 

